JP2602033B2 - Incandescent light bulb with infrared reflection filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an incandescent lamp with an infrared reflection filter.

[Prior art and problems] Conventionally, in an incandescent lamp having a filament inside a bulb, such as a halogen lamp, light emitted by heating the filament has a spectral characteristic as shown in FIG. Most of them are infrared light, and visible light is only about 15%. The visibility of human light is maximum at a wavelength of about 555 nm, but rapidly decreases as the wavelength shifts from this wavelength to the shorter wavelength side or the longer wavelength side. For this reason, the ratio of visible light to the total emitted light emitted from the filament of the incandescent lamp is very low.

On the other hand, there is a method of forming an infrared reflection filter on the outer surface of the bulb of the incandescent lamp in order to improve the radiation efficiency. This infrared reflection filter is formed by laminating thin films having different refractive indices. The interference effect of these laminated thin films allows visible light of radiated light to be transmitted from the filament and reflects infrared light. Then, the filament is further heated by the infrared light reflected by the infrared reflection filter, the temperature of the filament is increased, and the emitted light is increased. As a result, the radiated light is increased by the same electric input without increasing the electric input to the incandescent lamp, so that high radiation efficiency can be obtained.

However, in such an incandescent lamp with an infrared reflection filter, the infrared reflection filter includes a thin film made of a material having a different refractive index on an outer surface of the bulb of the incandescent lamp, and the optical film thickness, that is, the actual film thickness and the refractive index. The thickness of the outermost thin film made of a material with a low refractive index is made thinner than the other thin films, so that the visible light transmittance is reduced. Depending on the usage of the incandescent lamp, the infrared reflection filter is easily damaged from the outside. Therefore, when the outermost layer is relatively thin, the outermost layer is damaged by the above-mentioned damage. The thin film inside the thin film may be damaged, and the infrared reflection filter may be destroyed.

Further, such an infrared reflection filter has a reflectivity of about 25 to 37%, of which the rate of irradiating the filament is further reduced, so that the radiation efficiency is reduced.

[Object of the invention]

In view of the above, an object of the present invention is to provide an incandescent lamp with an infrared reflection filter, which has a high visible light radiation efficiency and is hardly damaged by outside.

[Means and actions for solving the problems]

According to the present invention, according to the present invention, a thin film made of a material having a different refractive index is alternately laminated on an outer surface of a bulb of an incandescent lamp at a film thickness selected so that its optical film thickness is equal. In an incandescent lamp with an infrared reflection filter formed by laminating an outermost layer thin film made of a material with a low refractive index, the optical film thickness of the outermost layer is 410 to 510 nm or 780 to 910 nm. Achieved by being selected.

According to the present invention, the optical thickness of the outermost thin film is formed relatively thick in a range that gives a low reflectance to visible light, so that the visible light radiation efficiency is high and damage from outside is caused. Even if the infrared reflection filter is damaged, it hardly occurs that the damage penetrates through the outermost thin film and reaches the thin film inside the outermost thin film. Therefore, the infrared reflection filter is hardly damaged by external damage.

〔Example〕

Hereinafter, the present invention will be described based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of an incandescent lamp with an infrared reflection filter according to the present invention. This incandescent lamp 1 with an infrared reflection filter has a TiO ₂ thin film 3 having a refractive index of 2.25 on a surface of a bulb 2 made of glass having a refractive index of 1.48.
And a SiO ₂ thin film 4 having a refractive index of 1.45 so that their optical film thickness (the product of the actual film thickness and the refractive index) is equal, for example, having an optical film thickness of 260 nm. The infrared reflective filter 6 having four to eight layers is formed by alternately laminating a predetermined thickness selected as described above and laminating the outermost thin film 5 made of SiO ₂ thereon.

Here, in the case where four infrared reflection filters 6 are formed, the reflection efficiency of the infrared reflection filter 6 with respect to the total radiated light and visible light from the filament of the incandescent lamp 1 with respect to the thickness of the outermost thin film 5 is as follows. This will be described with reference to the graph of FIG.

As shown by the symbol R1, it can be seen that the reflectance for the total emitted light does not vary much, but the reflectance R2 for the visible light varies periodically. That is, R2 ranges from 85 to 145 nm with the thickness of the outermost thin film 5 being about 120 nm as a peak, and about 44 nm.
Relatively low reflectance is provided in the range of 410-480 nm with a peak at 2 nm and 780-650 nm with a peak of about 822 nm. The radiation efficiency of the incandescent lamp 1 increases as the reflectance R1 increases and as the reflectance R2 decreases, so that the high radiation efficiency of the incandescent lamp 1 is obtained in the above-described range.

Thus, the thickness of the outermost thin film 5 can be appropriately selected within the above range under various conditions, for example, according to the possibility of external damage. And
In particular, the thickness of the outermost thin film 5 is in the range of 410 to 480 nm and 78.
In the range of 0 to 860 nm, the thickness of the outermost thin film 5 is sufficiently large, so that damage from the outside may not penetrate through the outermost thin film 5 to reach the thin film inside. Absent.

When the eight-layer infrared reflection filter 6 is formed on the outer surface of the bulb of the incandescent lamp 1, similarly, when the thickness of the outermost thin film 5 is in the range of 440 to 510 nm and in the range of 780 to 910 nm, The high radiation efficiency of the incandescent lamp 1 can be obtained, and the thickness of the outermost thin film 5 is sufficiently large, so that damage from outside penetrates through the outermost thin film 5 and damage is inside the thin film 5. It does not reach the thin film.

〔The invention's effect〕

As described above, according to the present invention, thin films made of materials having different refractive indices are alternately laminated on the outer surface of the bulb of an incandescent lamp at a thickness selected so that the optical thicknesses thereof are equal. An infrared reflective filter was formed by laminating an outermost thin film made of a material having a low refractive index thereon.In the incandescent lamp with an infrared reflective filter, the optical film thickness of the outermost thin film was 410 to 510 nm. Or 780-9
Since the optical film thickness of the outermost layer is relatively thick within the range that gives low reflectance to visible light, the radiation efficiency of visible light Is high, and even if it is damaged from the outside, it hardly happens that the damage penetrates the outermost layer and reaches the thin film inside, so the infrared reflection filter is damaged by the external damage Less to do.

Thus, according to the present invention, it is possible to provide an incandescent light bulb with an infrared reflection filter, which has a high radiation efficiency and is hard to be damaged from the outside, and is most suitable for automobiles and general lighting.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a part of a bulb surface of one embodiment of an incandescent lamp with an infrared reflection filter according to the present invention.
FIG. 5 is a graph showing the relationship between the optical thickness of the outermost thin film and its reflectance in the embodiment of FIG. FIG. 3 is a graph showing a spectral characteristic of light emitted from a filament of a conventional incandescent lamp. 1 ... Incandescent lamp with infrared reflection filter; 2 ... Bulb; 3
…… TiO ₂ thin film; 4 …… SiO ₂ thin film; 5 …… Outermost thin film; 6 ……
Infrared reflective filter; R1 ... reflectance for total emitted light;
R2: Reflectivity for visible light.

Claims (1)

(57) [Claims] 1. A thin film made of a material having a different refractive index is alternately laminated on an outer surface of a bulb of an incandescent lamp at a film thickness selected so as to have an equal optical film thickness. An infrared reflective filter with an infrared reflective filter formed by laminating an outermost thin film made of the material of the above, is an incandescent lamp with an infrared reflective filter, wherein the optical film thickness of the outermost thin film is 410 to 510 nm or An incandescent lamp with an infrared reflection filter, which is selected to be 780 to 910 nm.